In motor vehicles, use is increasingly being made of closed hollow profiles having cross sections and material thicknesses adapted specifically to the case of application. In the past, closed hollow profiles have generally been produced first by shaping a tube, subjecting the tube to appropriate bending or pre-deformation and subsequently carrying out hydroforming of the pre-bent or pre-deformed shape to form the final shape of the closed hollow profile. On the one hand, not all components can be produced in this way, as during the hydroforming local extensions of the material are exceeded, so that cracks can form. In addition, uncontrollable wrinkling can occur during the hydroforming. On the other hand, the previously used method steps for producing a closed hollow profile which is adapted to the application in question are very complex and thus cost-intensive. Although a closed hollow profile can in principle also be produced from two deep drawn half shells, stresses are introduced into the blank during deep drawing of a blank and can lead to springback of the blank. However, the springback of the half shells hinders precise positioning of the half shells in a die for welding. In the past, welding of the edges of the half shells in a butt joint was not possible without great expense owing to the springback of the half shells. For this reason, closed hollow profiles consisting of welded half shells have in the past conventionally been welded to the protruding flange regions. However, the protruding weld seam prevents these closed hollow profiles from being inserted like closed hollow profiles which are produced from a welded tube and have no protruding weld seam. Also, the flanges significantly increase the total weight of the component.
A method for producing half shells is known from published Japanese patent application JP 08/168830, in which method a blank is first deep drawn in a die, such that protruding flange regions are produced. The flange regions are subsequently upset and sheared off at the same time via an upper cutting and upsetting swage. However, owing to the geometry of the upper cutting/upsetting swage, the half shells thus obtained display non-uniformities at the edges of the half shells, so that said half shells are not suitable for welding in a butt joint. In addition, the known cutting/upsetting does not lead to sufficiently low-stress half shells which are suitable for being welded to one another in a butt joint.